Micrononuniformity effects in thin-film photovoltaics

We discuss the effects of micrononuniformities on thin-film photovoltaics. The key factors are the device large area and the presence of potential barriers. We model the nonuniformity effects in terms of random microdiodes connected in parallel through a resistive electrode. Microdiodes of low open circuit voltage affect macroscopically large regions. They strongly reduce the device performance and induce nonuniform degradation in several different modes. We support our predictions with experimental results on CdTe/CdS dot cells.